The open source software community has published a substantial body of research on OSS quality. Focusing on this peer-reviewed body of work lets us draw conclusions from empirical data rather than rely on the large volume of evangelical opinion that has historically dominated this field. This body of published research has become much more critical and objective in its efforts to understand OSS development, and a consensus has emerged on the key components of high-quality OSS delivery. This article reviews this body of research and draws out lessons learned, investigating how the approaches used to deliver high-quality OSS differ from, and can be incorporated into, closed-source software development.